total += read;
      Java8Compatibility.clear(buf);
    }
    return total;
  }

  /**
   * Discards {@code n} characters of data from the reader. This method will block until the full
   * amount has been skipped. Does not close the reader.
   *
   * @param reader the reader to read from
   * @param n the number of characters to skip

  }

  private static int mixH1(int h1, int k1) {
    h1 ^= k1;
    h1 = Integer.rotateLeft(h1, 13);
    h1 = h1 * 5 + 0xe6546b64;
    return h1;
  }

  // Finalization mix - force all bits of a hash block to avalanche
  private static HashCode fmix(int h1, int length) {
    h1 ^= length;
    h1 ^= h1 >>> 16;
    h1 *= 0x85ebca6b;
    h1 ^= h1 >>> 13;
    h1 *= 0xc2b2ae35;
    h1 ^= h1 >>> 16;

  /**
   * Interrupts the running task. Because this internally calls {@link Thread#interrupt()} which can
   * in turn invoke arbitrary code it is not safe to call while holding a lock.
   */
  @SuppressWarnings("Interruption") // We are implementing a user-requested interrupt.
  final void interruptTask() {
    // Since the Thread is replaced by DONE before run() invokes listeners or returns, if we succeed

    }

    @Override
    public E element() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.element();
    }

    @Override
    public Iterator<E> iterator() {
      // We explicitly don't lock for iterator()
      assertFalse(Thread.holdsLock(mutex));
      return delegate.iterator();
    }

    @Override
    public int size() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.size();

  protected void shutDown() throws Exception {}

  /**
   * Invoked to request the service to stop.
   *
   * <p>By default this method does nothing.
   *
   * <p>Currently, this method is invoked while holding a lock. If an implementation of this method
   * blocks, it can prevent this service from changing state. If you need to performing a blocking
   * operation in order to trigger shutdown, consider instead registering a listener and

  protected void shutDown() throws Exception {}

  /**
   * Invoked to request the service to stop.
   *
   * <p>By default this method does nothing.
   *
   * <p>Currently, this method is invoked while holding a lock. If an implementation of this method
   * blocks, it can prevent this service from changing state. If you need to performing a blocking
   * operation in order to trigger shutdown, consider instead registering a listener and

          timeoutFuture.timer = null; // Don't include already elapsed delay in delegate.toString()
          String message = "Timed out";
          // This try-finally block ensures that we complete the timeout future, even if attempting
          // to produce the message throws (probably StackOverflowError from delegate.toString())
          try {
            if (timer != null) {

// advanced techniques like specifying lock strength and optimizer hints. See the
// [docs] for more depth.
//
//	// add a simple limit clause
//	db.Clauses(clause.Limit{Limit: 1}).Find(&User{})
//	// tell the optimizer to use the `idx_user_name` index
//	db.Clauses(hints.UseIndex("idx_user_name")).Find(&User{})
//	// specify the lock strength to UPDATE
//	db.Clauses(clause.Locking{Strength: "UPDATE"}).Find(&users)

		// Write the initial GNU header.
		var blk block
		gnu := blk.toGNU()
		sparse := gnu.sparse()
		copy(gnu.realSize(), size)
		sps = populateSparseMap(sparse, sps)
		if format != FormatUnknown {
			blk.setFormat(format)
		}
		out = append(out, blk[:]...)

		// Write extended sparse blocks.
		for len(sps) > 0 {
			var blk block
			sps = populateSparseMap(blk.toSparse(), sps)

			totalDrives:   totalDrives.Sum(),
			ioStats:       map[string]driveIOStatMetrics{},
		}

		currentStats := getCurrentDriveIOStats()
		now := time.Now().UTC()

		prevDriveIOStatsMu.Lock()
		if prevDriveIOStats != nil {
			duration := now.Sub(prevDriveIOStatsRefreshedAt)
			if duration.Seconds() > 1 {
				for d, cs := range currentStats {
					if ps, found := prevDriveIOStats[d]; found {